Front-end loaders are machines designed to relocate, lift, and dump a variety of materials. A vehicle can be manufactured expressly for the purpose or an existing tractor can be equipped with a loader attachment. The front-end loader will have a lift arm assembly pivotally attached at one end to the vehicle and pivotally attached at the other end to a bucket or other type of material handling implement. Hydraulically actuated lift cylinders pivotally mounted at one end to the lift arm assembly and pivotally mounted at the remaining end to the frame of the vehicle or tractor raise and lower the lift arm assembly with hydraulic pressure received from a hydraulic system established on the vehicle. Tilting or dumping of the material handling device is accomplished by the extension or retraction of the hydraulically actuated bucket tilting cylinder or cylinders acting through arms and links attached at a pivot point or the material handling implement or bucket on one end and on the other end to a pivot point located static to the vehicle. These arms and links in series with the hydraulic cylinder are designed and located to maintain a substantially fixed and pre-selected orientation of the bucket throughout the raising and lowering cycle of the lift arm assembly.
Many self-orienting designs place limitations upon the maximum amount of rotation allowed the lift arm assembly and bucket. Usually to accomplish the desired operation at either the extreme lowered or raised position of the lift arms a compromise situation is experienced at the other extreme position. That is to say that a self-orienting bucket design that has a favorable angle between the bucket actuating mechanism and the bucket at extreme tilt-back position when lift arms are lowered to extreme position can experience a problem with interference and or critical angles between components of the linkage, lift arms, and bucket when lift arms are raised to extreme limits and the bucket is tilted down or dumped to extreme position. Considerations must be made in the design of the linkage mechanism substituting desirability with acceptability.
Another disadvantage with some designs is the extreme upper and lower travel of the lift-arm assembly is restricted by limitations of the self-orienting mechanism and not the physical limits that exist between the lift arm assembly and the vehicle.
Limitations common to many self-orienting loader designs occur while the lift arm assembly is fully raised not allowing the bucket to achieve a filly dumped orientation before the bucket-tilting cylinder reaches maximum extension. Most stop considerably short of straight down making it difficult to dump materials that tend to stick and not slide from the dumped bucket.
Improvements to the above-described problem areas realized through a unique self-orienting bucket mechanism will be an enhancement to the current art.